The Cause of the Problems with Dimensional Tolerancing
Although dimensional tolerances may appear to be arranged in a coordinate system, on a real component they are not. The component in the video below can meet all the dimensional tolerances, while having significant, unpredictable deviations.
With this type of tolerancing, your supplier will not know which angular relationships are important and have to be maintained and which are less important. The result is that he either tries to maintain them all and makes the component more expensive than necessary, maintains none of them — in which case the component is unlikely to function — or he tries to guess which ones are important and probably guesses wrong. In any case, it is not your supplier’s responsibility if the component does not work, as long as he meets the dimensional tolerances.
When you try to limit these deviations with geometrical tolerances one by one, as you detect them in production, you have hybrid tolerancing.